oracle按指定时间查询数据如果未查询到继续递减时间段查询(存储过程)

CREATE OR REPLACE PACKAGE GetEcData is
type outlist is ref cursor;
Procedure p_GetTimeData(from_date in date, return_list out outlist);
END GetEcData;


CREATE OR REPLACE package body GetEcData is 

Procedure p_GetTimeData(from_date in date, return_list out outlist) 
is 
v_count number(32):=0;
execount number(32):=0;
over_date date:= from_date - 10/1440;
begin 
      
      Loop
        select count(datavalue) into v_count from ec_datab where timedata <from_date and timedata >=over_date ;
         if v_count > 0 then
            open return_list for select * from ec_datab where timedata <from_date and timedata >=over_date ;
            exit;
         end if;
             over_date  := over_date  - 10/1440;
     if over_date<to_date('2008-1-1','yyyy-mm-dd') then
dbms_output.put_line('未检索到数据!已到日期下限!停止查询!');
exit;
end if;
     end loop; 
end ;
end GetEcData;